The present invention relates to antennas and more particularly to a thin ultra-broadband antenna with conductive elements in a single plane.
The optimum three-dimensional shape for a broadband dipole, as concluded by antenna researchers, is a dipole consisting of two opposed xe2x80x9clight bulbxe2x80x9d shaped elements. The optimum shape for a broadband planar monopole over an orthogonal, infinite ground plane is believed to be elliptical or circular. The optimum shape for a planar dipole or a planar monopole with a co-planar finite ground plane has not previously been addressed.
U.S. Pat. No. 4,605,933 to Butscher discloses a microstrip antenna with a lower ground plane, a spaced rectangular upper ground plane and a circular radiating element coplanar with the upper ground plane. The disclosed antenna requires an impedance matching arrangement to connect to a transmission line. The disclosed antenna has the configuration of a microstrip antenna with the lower ground plane in a second spaced plane, and is thus not a planar antenna. U.S. Pat. No. 6,329,950 to Harrell et al. discloses a planar antenna with concentric elements. An inner circular element within a rectangular outer element is disclosed. The inner and outer elements are separated by a gap, but electrically connected across the gap by a shorting element and a coaxial cable feed.
The frequency range of 825 MHz to 6 GHz covers numerous wireless bands, including the cellular/GSM, PCS, ISM, MDS/MMDS and UNII bands. An ultra-broadband antenna that operates across the frequency range of 825 MHz to 6 GHz is desirable. A very thin ultra-broadband antenna that is simple and inexpensive to produce is also desirable.
An antenna includes an electrically conductive, planar antenna portion, a transmission line and a housing. The antenna portion has an elliptical first element and a rectangular second element. The first and second elements are spaced, adjacent and co-planar. The transmission line has a first conductor directly connected to the first element and a second conductor directly connected to the second element. The housing encloses the antenna portion.